Transmitter.



Rt S. M. MITCHELL.

VI'RANSMT'R.

APPLIUMION FILED MAR. 29 m2 Patented Mar. 1.8,

i-mj 2@ HV/f /f 0024 3g if Q3 sistance.

.Lii

RICHARD S.

MITCHELL, 'DE SYRACUSE, N'EW YORK,

@i i rnv@ in entre ik itl li it" Specification of Letters fatent. Yraya 18 figli@ 3 To all w/iom may concern.'

Be it known that lieifano S. M. lilircnni.n a citizen of the Jnited States, residing at Syracuse.,y in the county ot @nondaga and State olf New York, have invented certain new and Useful Improvements in Transmitters, or' which the following is a specification.

rlhis invention relates to improvements in.

traiisinitters, and has for its object to provide a novel. simple and effective device of the class, which is capable of being,r einplojtfed for the recording and reproducing of vibrations corresponding to the sounds or voices. inusic and the like, whether used in connection with elcctrographs, talking machines or the connnon telephones.

.fr further object is to provide a transmitter which is capable of giving a greater, more uniform and more delicate. means tor introducing a variable resistance into the primary circuits of the traiistnitteru nd a further object is to provide a transmitter wherein the construction and arrangement o1 the parts are such that all the troubles incident to the pnlverizing oit' the carbon which frequently occurs in the most irnproved forms of granulated-carbon and solid-back transmitters is entirely eliininated.

Figure l is a top plan View of the transmitter. Fig. 2 is a central vertical section through the transmitter; showing, the construction and arrangement of the same. Fig. 3 is an enlarged detail View showing a strip of carbon from which the electrodecoils are made. Fie. 4. is an enlarged View of one of the carbon coils; showing the same relaxed for offering the full measure of reis a similar View sl'iowing the cai-hon coil partly compressed for decreasing.' the resistance or' the electrode. Fig. t3 is a View; showing a plain diaphragm for use in makingr records.

ln the. drawing, 2 represents solid Circular cap pieter-ably made of hard ruloher or like insulating niate ial, haring a hollow interior or chamber 3 l represents a hase of the sa 'ne material, which is also circular in forni and which may be secured to the en; by any suitable means. '.'l'ie hase t is also solid except `for a narrow four-way slot 5, in which certain. of the Vibrating parts are disposed when the ytransmit-ter is used for.

reproducing vibrations i3 represents a iliai'ihragni, preferably made ot steel and circular in form, which Yis disposed hetween the cap and oase 4i, and rests upon a felt or other like rin T, which supported by the hase l. (')therwise the diaphragm is unsupported.

represents a shallow recess or cavity formed in the hase l for allowing` the diaphragm to ritirate freely. The arrange nient ot' the top 2 and hase l is such that when joined together they forni a hollow fasing for inclosing and protecting the working parts .o'i' the transmitter.

Si rei-)resenls .fiy series ot electrodes, which a be prelerahly inadeor" thin tapering strips 9 ot pure carbon. The said strips may loe inode olE any other suitable material. which offers adequate resistance. The electrodes t) are preferably made in the forni ot cylinders comprising a spiral winding ot the strips fl', as shown. Vllhe arrangement of the electrodes 9 is such that the coiivolutions increase in width gradually from t e hottoni toward the top of the coil, and thesaid convolutions when normal are intended to ne evenly spaced apart by a small fraction. of an inch, preferably from lire lo ten one thonsandths of' an incln rThe object ot the said construction is to provide a resilient spiral Acai-hon electrode which is extremely sensitiye to compression and relaxation when acted upon by the vibrating diaphragm o. for decreasing and increasingr the resistance in the circuit controlled by each electrode. The electrodes ll are preferably mounted upon an inwardly facing shelf or ledge l0, upon which they are held in ver-- tical position hv loolts or rods ll, which pass through and are snp-ported hy caps lf2,-

which are mounted on the tops or the coils i, the caps or head pieces l2 preferably comprising an insulating material. Ey this arrangement the. upward and downward movements or" the rods ll, acting througlir the caps or heads l2? effect the compression or relaxation et the carbon springs 9. i

lr have shown onr electrodes 9 disposed at equal distances around the chamber 5% or the cap "2, but a greater or less number ot the eleetrodes may he employed in connection with the transmitter, if desired. The electrodes 9 in the present ease are arranged vertically, hat. they may disposed horisontall f or in any suitable position, and instead o simple levers lil any other suitupon @Y sufi Imct he mma e cominci mm o he Same mim@ may subs @Jaivng Smm rin f" mm3 wasted er zehui' 51 graduali, and neve? Non s.

Combmau ximg' movem'eus for magntmg A the opening and 

